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New Mexico fossil tells survival story

From reports
Published 12:37 p.m. MT Oct. 6, 2015

Geology student finds fossilized teeth in San Juan Basin

The group that worked on discovery in the San Juan Basin last summer were from left, Sarah Shelley, Eric Daviidson, Carrisa Raymond, who was the student who found the fossil, Steve Brusatte and Ross Secord.(Photo11: Courtesy)

Story Highlights

A new fossil from an ancient group of mammals is providing scientists with information about how mammals survived a mass extinction and flourished in the aftermath.

The fossil is from a group of mammals known as multituberculates that lived along with the dinosaurs for 100 million years. They were mostly small and resembled today’s rodents, with enlarged incisors and molars with many cusps. Some may have fed on plants and leaves.

A sketch of Kimbetopsalis simmonsae by one of the authors of the paper on the fossil's significance.(Photo11: Courtesy/Sarah Shelley)

The teeth of a new fossil from an ancient group of mammals rest in an anthropologist's hand.(Photo11: Courtesy/Ruidoso Newsnature)

They were among the few land animals that survived the extinction that killed the dinosaurs. After the extinction, they thrived for a brief time, but then dwindled to extinction about 35 million years ago. They may have been out-competed by rodents.

The new species, Kimbetopsalis simmonsae, was found in the San Juan Basin of northwestern New Mexico last summer. It helped scientists reconstruct the family tree of the particular group of multituberculates, which includes the biggest species of multituberculate, Taeniolabis, that weighed as much as 100 killigrams, about the size of a large beaver. Kimbetopsalis simmonsae lived only about 500,000 years after the dinosaur extinction. It may have been a forebear to Taeniolabis, was a bit smaller and occurred about 200,000 years earlier.

During her first fossil-hunting trip, University of Nebraska-Lincoln student Carissa Raymond found the specimen of the previously unknown mammal species from about 65 million years ago, according to a University of Nebraska press release. "Raymond, a junior geology and geography major from Seward, was one of three students recruited by UNL paleontologist Ross Secord to assist with fieldwork in the San Juan Basin in New Mexico in 2014," the release stated. "Three or four days out, she spotted several strange black teeth lying exposed in the grit of an area known as Kimbeto Wash."

The study, carried out by the New Mexico Museum of Natural History and Science, the University of Edinburgh, and the University of Nebraska, was published in the "Zoological Journal of the Linnean Society." It was supported by the Marie Curie Foundation, the Natural Environment Research Council, the U.S. Bureau of Land Management, and the National Science Foundation.

Dr Thomas Williamson of the New Mexico Museum of Natural History and Science, who led the research, said, “New Mexico is especially famous for its record of Paleocene mammals. Fossils such as these are critical for telling us how animals survived truly catastrophic environmental change. Multituberculates were among the first mammals to thrive in the post-apocalyptic world following the mass extinction that killed the dinosaurs.”